Not having played it (and maybe not for a long time since my laptop can't even remotely handle Crysis 3) it is rarely a good idea to go in guns blazing.. unless you are a gamer god with the reflexes of a 16 year old and your whole free time devoted to shooter games.

It's always like this in the beginning.. skills suck, your equipment sucks and your gear sucks. It almost always gets better after about a third of the game.

I completed it in about six hours of sit time. The campaign is quite short but it is solid. Once i figured out how to play it with my perfered play style it was ok. I had to knock the difficultt back on the final boss though. Mp is ok, but fps mp isnt really my thing.

I have not played warhead, I probably wont. My memory of the first crysis is faded and I never played the second one. Given the short single player campaign the game is easily more focused on multi-player, but it is not the free-to-play style that warhead is suppose to be.

There are weapon and skill unlocks at certain levels, but nothing too game breaking I dont think, but I am only level 12 in MP and mostly that's because of my kids playing it.

I haven't played Crysis 3 yet, but in Crysis 2 it was never a good idea to go guns blazing into the area filled with enemies. Usually you'd be dead in about 5 seconds. Stealth is the way to play this game effectively.

I found what worked for me in most situations was to go stealth in the crouching position until about I was 1/3 from empty, get into the spot I pre planned to sit in while my energy came back. Rinse and repeat. I killed what I had to or thought I could do with minimal effort.

I actually really liked the latest game. The campaign was shorter than the other games, which was disappointing, but I enjoyed the games focus on the story and the characters this go-through. The Predator Bow makes the game stupid-easy if you spend the whole game cloaked and using the bow. I ended up only rarely using the bow just to keep it more interesting. Fun game. They certainly seem to wrap the story-line up, but since the game did well enough for 3.5 games, I'm sure they'll come up with a way to do a Crysis 4.

I played through the first one three times, because of the possibilities the open world offered. Only played through Warhead once, because the bugs kept pissing me off (e.g., several enemy units that had to be destroyed to complete story flags had somehow become invincible and required a reload).
Crysis 2 was a major disappointment, because the resulting rail shooter we ended up with was crippled beyond hope, just to allow the console kiddies to keep up (something I couldn't care less about as a PC player).
After I found out that the rumored return to open world tactics in Crysis 3 was just exaggerated PR bullshit I didn't even buy the game anymore and only watched some Youtube videos of the end to get closure.